I'm hoping you folks can point me to "official" research showing the smallest level difference people can hear. The general consensus is that level changes as small as 1/2 or even 1/4 dB can be perceived under some conditions. And I'm sure there's a ton of research to back this up. But all I've been able to find with Google are statements to that effect, some on university web sites, but with no actual references to past research. Surely this has been published many times?

I tested this myself once. I could ABX 0.5 dB with actual music, but it was fairly difficult. I could not ABX lower. I suspect with properly chosen pure tones more subtle differences may be noticeable, but I was only concerned with real music.

That seems to be JND for amplitude modulation at 4 Hz, versus absolute volume differences.

No! That search string was intended to lead you to the book "Psychoacoustics: Facts and Models" by Zwicker and Fastl, which has an entire chapter on that topic (chapter 7, hence the "7 ..."). You should be able to browse that book through Google Books. Recommended buy, btw.

Edit: Figure 7.1 already tells us a lot about the impressive JND sensitivity to certain tones at certain levels, which supports saratoga's claim.

Probably not the "official" research you're looking for, but FWIW, there are some user reports of audible small differences, including mine for 0.1dB. I think that I might be able to do even less than 0.1dB (I'll give it a try one of these days).

Apparently, from what I've heard, to find the lowest JNDs you need to use young teenagers from primitive cultures (no exposure to amplified sound/motor noise/subway etc) in an isolated soundproof room, using headphones, listening to narrow band noise (not pure tones, which was more common in such research in the past), centered at around 3.5 kHz or a little higher, at a slightly annoyingly loud level they'll not choose of their own accord, with rapid-fire A/B switching.

Some historical references, including a chart that won't cut and paste nicely to here (but I tried), below, taken from here.

I tried something else. How does that look? Better than all those CRLFs and massive amounts of whitespace, I think! It wasn’t difficult to fix, so please take the couple of minutes that would be needed in future cases.

Differences as small as 3 millibels have been repeatedly detected in otherwise identical equipment.

I've participated in non-blind listening tests where "Differences as small as 0 millibels have been repeatedly detected."Did the poster give any references for his 3 mB JND claim or was it just another attempt to keep forums busy ?

I tried something else. How does that look? Better than all those CRLFs and massive amounts of whitespace, I think! It wasn’t difficult to fix, so please take the couple of minutes that would be needed in future cases.

Thanks, that looks much nicer.

I'm sure you are correct that it was not difficult for you to fix, however you have some knowledge about cutting and pasting charts/diagrams from websites to forum text that I don't possess. My failure to present the data in a nice compact chart had nothing to do with my "not taking the couple of minutes necessary", but rather my complete lack of training in such matters. (Nor the software necessary, unless Windows itself has this chart manipulation/conversion software built in and I just don't know where nor how to use it.)

I've never heard of "CRLFs" but Googling it I doubt you mean "Consolidated Resources for Lego Fire Services" [Ha ha.] but rather "carriage return line feeds". Now knowing this acronym's individual words still doesn't gain me the knowledge to cut and paste charts in the future, however. Please tell me what program you are using to manipulate the chart when you paste it here, and I will be able to hopefully download the program for free and learn how to do this on my own for future use.

Differences as small as 3 millibels have been repeatedly detected in otherwise identical equipment.

I've participated in non-blind listening tests where "Differences as small as 0 millibels have been repeatedly detected."Did the poster give any references for his 3 mB JND claim or was it just another attempt to keep forums busy ?

3 milliBels is .3 dB, which is in fact, for time-proximate stimulii, not entirely out of the question.

I'm sure you are correct that it was not difficult for you to fix, however you have some knowledge about cutting and pasting charts/diagrams from websites to forum text that I don't possess. My failure to present the data in a nice compact chart had nothing to do with my "not taking the couple of minutes necessary", but rather my complete lack of training in such matters. [. . .] Please tell me what program you are using to manipulate the chart when you paste it here, and I will be able to hopefully download the program for free and learn how to do this on my own for future use.

Heh, it was nothing refined: I just used Notepad to align the columns using spaces in a fixed-width font and then pasted that into a [ codebox], which (like [ code]) preserves fixed-width characters and multiple spaces, unlike normal fonts. I would probably be stuffed if I had to do anything actually complicated, so we’re the same here. I apologise for the way I worded that.

No! That search string was intended to lead you to the book "Psychoacoustics: Facts and Models" by Zwicker and Fastl, which has an entire chapter on that topic (chapter 7, hence the "7 ..."). You should be able to browse that book through Google Books. Recommended buy, btw.

QUOTE (mzil @ Jan 21 2012, 01:29)

Some historical references, including a chart that won't cut and paste nicely to here (but I tried), below

Excellent, thanks to all. And Chris, I did try to browse through that book's chapter, but it kept leaving out pages, so all I was able to see referred to AM audibility.

Yeah, I've seen that, and other tests for threshold levels. By total coincidence, I had my hearing tested on Thursday. First time in probably 30 years. As expected, my thresholds are not what they once were, but the doc said it's within a normal range for someone my age of 63.